1. Field of the Invention
The present invention generally relates to a portable radio apparatus having multiple antennas and, in particular, to the antenna extending and retracting mechanism of a portable radio apparatus.
2. Description of the Related Art
In a portable radio apparatus, spatial diversity can be implemented using multiple antennas. Some radio apparatus are provided with a pair of antennas and others with a retractable antenna and a built-in antenna incorporated in the housing thereof. In the case of the radio apparatus having a pair of antennas, it is preferable that these two antennas are mechanically linked so as to be simultaneously extended and retracted. Such an antenna extending and retracting mechanism has been disclosed in Japanese Patent Unexamined Publication No. 4-330830, as shown in FIG. 1.
Referring to FIG. 1, two retractable antennas 11 and 12 providing spatial diversity are implemented in the body 10 of a radio telephone apparatus. These two antennas 11 and 12 are mechanically linked through two cords 15 riding on two pulleys 13 and 14, respectively, so that they are simultaneously extended and retracted in opposite directions.
However, such a cord-and-pulley arrangement is complicated and needs rather large mounting space within the housing, resulting in the reduced space for implementing electronic devices. Therefore, according to the conventional mechanism, it is difficult to reduce the size and weight of the portable radio apparatus.